import java.util.*;

/**
 * @Author 12629
 * @Date 2022/3/19 15:31
 * @Description：
 */

public class TestBinaryTree {

    static class TreeNode {
        public char val;
        public TreeNode left;
        public TreeNode right;

        /**
         * 构造方法，构造一个节点
         *
         * @param val
         */
        public TreeNode(char val) {
            this.val = val;
        }
    }

    public TreeNode creteTree() {
        TreeNode A = new TreeNode('A');
        TreeNode B = new TreeNode('B');
        TreeNode C = new TreeNode('C');
        TreeNode D = new TreeNode('D');
        TreeNode E = new TreeNode('E');
        TreeNode F = new TreeNode('F');
        TreeNode G = new TreeNode('G');
        TreeNode H = new TreeNode('H');

        A.left = B;
        A.right = C;
        B.left = D;
        B.right = E;
        E.right = H;
        C.left = F;
        C.right = G;
        return A;//根节点
    }


    // 前序遍历
    void preOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        System.out.print(root.val + " ");
        preOrder(root.left);
        preOrder(root.right);
    }

    // 中序遍历
    void inOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        inOrder(root.left);
        System.out.print(root.val + " ");
        inOrder(root.right);
    }

    // 后序遍历
    void postOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        postOrder(root.left);
        postOrder(root.right);
        System.out.print(root.val + " ");
    }

    public static int count = 0;

    // 获取树中节点的个数         遍历思路：
    public void size1(TreeNode root) {
        if (root == null) {
            return;
        }
        count++;
        size1(root.right);
        size1(root.left);
    }

    /**
     * 子问题的思路
     *
     * @param root
     * @return
     */
    public int size2(TreeNode root) {
        if (root == null) {
            return 0;
        }
        //root不为空
        int tmp = size2(root.left) + size2(root.right) + 1;
        return tmp;
    }


    // 获取叶子节点的个数  遍历思路
    public static int leafCount = 0;
    void getLeafNodeCount1(TreeNode root){
        if (root == null) {
            return;
        }
        if(root.left ==null && root.right == null){
            leafCount++;
        }
        getLeafNodeCount1(root.right);
        getLeafNodeCount1(root.left);
    }


    // 获取叶子节点的个数  子问题
    int getLeafNodeCount2(TreeNode root){
        if (root == null) {
            return 0;
        }
        if(root.left ==null && root.right == null){
            return 1;
        }
        return getLeafNodeCount2(root.left) + getLeafNodeCount2(root.right);
    }

    int getKLevelNodeCount(TreeNode root,int k){
        if (root == null) {
            return 0;
        }
        if(k == 1){
            return 1;
        }
        return getKLevelNodeCount(root.left, k--) + getKLevelNodeCount(root.right, k--);
    }

    // 获取二叉树的高度
    int getHeight(TreeNode root){
        if (root == null) {
            return 0;
        }
        int treeLeft = getHeight(root.left);
        int treeRight = getHeight(root.right);

        return treeLeft > treeRight ? treeLeft + 1 : treeRight + 1;
    }



    // 检测值为value的元素是否存在
    TreeNode find(TreeNode root, int val){
        if(root.val == val){
            return root;
        }
        TreeNode ret = find(root.left,val);
        if (ret != null) {
            return ret;
        }
        TreeNode ret1 = find(root.right,val);
        if (root.right.val == val) {
            return root.right;
        }
        return null;
    }


    // 判断一棵树是不是完全二叉树
    boolean isCompleteTree(TreeNode root) {
        Queue<TreeNode> queue = new LinkedList<>();
        if(root != null) {
            queue.offer(root);
        }

        while (!queue.isEmpty()) {
            TreeNode cur = queue.poll();
            if(cur != null) {
                queue.offer(cur.left);
                queue.offer(cur.right);
            }else {
                break;
            }
        }
        while (!queue.isEmpty()) {
            TreeNode cur = queue.peek();
            if(cur != null) {
                return false;
            }else {
                queue.poll();
            }
        }
        return true;
    }

}